A 3V gM C-filter with on-chip tuning for CDMA

This paper describes a low-voltage channel selection analog front-end with continuous-time filters and on-chip tuning. The filters were realized as balanced seventh order elliptical g_m C-filters to achieve low current consumption. A novel floating resistor based transconductor was developed to satisfy stringent intermodulation distortion specification and to fulfil the requirement for low supply voltage. A novel biasing for high-swing cascode output stages that extends the practical signal swing capability was developed. A digital tuning circuit based on a time-domain integrator was realized